Shading devices have been traditionally used to reduce the area of glazing which is exposed to an influx of solar radiation.
Operable shading devices mounted exterior to windows are designed to control the incoming solar radiation. They may have a complex mechanism which requires maintenance or replacement, or may have an expensive automatic control system.
Other types of shading devices, such as roller shades, curtains or Venetian blinds, are installed within the interior of a building and are adapted to reflect incoming solar radiation back through the window before it can be absorbed and converted to heat. Recently, internal blinds, i.e. Venetian blinds that are arranged in a spaced parallel relationship and are placed between glass sheets in a double glazing unit or between the frames of a double window, have been employed.
Prior art Venetian blinds, must remain in an upright position, such that a longitudinal axis coinciding with each slat is essentially perpendicular to horizontally disposed flooring, during transportation, installation and while in use so that the slats and cords will not be in a state of disarray and be rendered unusable. If the longitudinal axis of the blind arrangement were not in an essentially vertical disposition, some of the blinds would touch the glazing, causing the cords which support the blinds to become entangled.
Venetian blinds are generally provided with at least two ladder braids, the number of ladder braids depending on the length of the slats. Each ladder braid is composed of two outer cords for tilting the slats, an inner cord for raising and lowering the slats, and a plurality of cross ladders. Each of the cross ladders is connected between the two outer cords and supports a corresponding horizontally disposed slat. The outer cords of prior art Venetian blinds, which provide a tilting motion, are directed to the tilting mechanism by means of a spacer placed on the outside of the uppermost slat. As a result, the weight of the slats is concentrated disproportionally more on the spacer and the uppermost slat than on the other slats, causing the slats to change their relative position, or even to fail, over the course of time. The tilting mechanism is usually a gear train that adds to the cost of the blind unit. Also, due to the angle of the cords the blinds cannot completely close and invariably only 75% of the incoming light is blocked.
Concerning the raising and lowering of prior art internal Venetian blinds, the actuation is generally by means of a magnet external to the glazing which linearly translates another magnet imbedded within the raising mechanism. The degree of raising or lowering of the blind is completely dependent on the displacement of the external magnet, and may take up to 2 minutes to raise the blind from a lowered position to a raised position. Due to the configuration of the cord and spacers, the area of the blind is limited to 2 sq. meters. A considerable force must be applied in order to raise the blind.
U.S. Pat. No. 3,702,040 discloses a Venetian blind structure that is adapted to be mounted within the air space of a double glazed sealed window unit. A plurality of elongated slats are pivotally mounted at their ends in a support frame, such that pins which protrude from a wheel secured to the pivot shaft of each slat abut transverse edges of a reciprocable actuating member driven by a gear train and therefore limit the angular position of the slats. The gear train is adapted to tilt the slats, but the Venetian blind structure is not provided with a means to raise or to lower the slats. Also the addition of the gear train adds to the cost of producing and assembling the blind structure.
U.S. Pat. No. 6,059,006 is another actuation device for adjusting the inclination of Venetian blinds arranged inside a double glazing unit. A first magnet is slidingly movable inside the sealed space of the double glazing unit, in response to the movement of a second magnet, which is located inside a box-like body connected outside the double glazing unit and driven by a cord stretching in a loop between two pulleys and connected to an actuation rod. The first magnet is fixed to a bush which is internally shaped complementarily to the helical profile of a shaft, so that translatory motion of the first magnet results in rotation of the shaft and of vertical adjustment chords to thereby synchronously adjust the inclination of the blinds about a longitudinal axis thereof. The complexity and cost of the apparatus is increased, due to the transmission system, as well as the actuator that is external to the double glazing unit.
U.S. Pat. No. 6,095,223 discloses an actuation unit that includes a magnetic kinematic coupling device which is connected to an electric motor and to a kinematic system for moving an internal Venetian blind. The apparatus of the actuation unit adds to the cost of the Venetian blind.
Other manually operated Venetian blinds mounted in a double glazing unit are disclosed in EP 0 245 811, EP 1 087 095, EP 0 902 155, U.S. Pat. Nos. 4,685,502, 4,768,576, US 2003/0089462, and US 2004/0211528.
It is an object of the present invention to provide a Venetian blind assembly which is incorporated in a permanently sealed double glazed window unit.
It is an object of the present invention to provide an internal Venetian blind assembly that provides for the tilting, raising and lowering of the slats.
It is an additional object of the present invention to provide an internal Venetian blind assembly in which means for tilting, raising and lowering of the slats are disposed internally to the double glazed window unit.
It is an additional object of the present invention to provide an internal Venetian blind assembly for which means for tilting, raising and lowering of the slats are manually actuated.
It is an additional object of the present invention to provide an internal Venetian blind assembly for which the tilting, raising and/or lowering of the slats can be reliably completed within approximately 2 seconds.
It is an additional object of the present invention to provide an internal Venetian blind assembly for which means for tilting, raising and lowering of the slats are relatively frictionless and can be easily assembled.
It is an additional object of the present invention to provide an internal Venetian blind assembly in which the means for tilting, raising and lowering of the slats do not incorporate a gear train, a set of pulleys or couplings.
It is yet an additional object of the present invention to provide an internal Venetian blind assembly that can be inverted without resulting in cord entanglement and can be operable immediately thereafter.
It is yet an additional object of the present invention to provide an internal Venetian blind assembly by which the slats may be tilted, raised and lowered while the blind assembly is disposed at an inclination of approximately 45 degrees with respect to the floor.
It is yet an additional object of the present invention to provide an internal Venetian blind assembly that blocks approximately 90% of the incoming light.
It is yet an additional object of the present invention to provide an internal Venetian blind assembly that overcomes the disadvantages of the prior art.
Other objects and advantages of the invention will become apparent as the description proceeds.